Telegraph repeater



AUS 8, 1950 J. A. KREcEK 2,518,027

TELEGRAPH REPEATER y i /Nl/ENTOR JAX/9565K AroR/VEV Patented Aug. 8, 1950 'PATENT o FFICE YTEIEGRAPH REPEATER Joseph A. Krecek,vNew Rochelle, N. Y., assigner i to Bell Telephone Laboratories, Incorporated, New York, N. Y., al corporation of New York Application May 18, 1946*,` Serial No. `670,684 i 11 claims. (ci. 173%71) This invention relates to telegraph repeaters and ,particularlyv to electronic regenerative repeaters.

An object of the invention is to minimize the number of electromagnetic relays required to repeat telegraph signals regeneratively.

Another object of the invention is to control the regenerative retransmission of `signals by means of gas-nlled electron discharge tubes.

Another object of the invention is to employ an electron discharge tube as a transmitter of direct current telegraph signals. l The invention features a circuit arrangement in which the current through the winding of a telegraph signal transmitting relay. is reversed and thereafter restored to initial direction by virtue of the ring and subsequent quenching of a gas-lled electron discharge tube.

The invention is contemplated in two Aembodiments. Each of the embodiments of the invention is a two-way half-duplex electronic. re-. generative repeater by which is meant that transmission may proceed in either direction through the repeater, one direction at a time. In accordance with one embodiment of the invention each of the two lines to be interconnected by the repeater is terminated in a loop which includes the operating winding of a receiving relay and the armature and marking contact `of a transmitting relay. A series circuit from :posi-- tive battery'through the armature and marking contacts of both receiving relays to the anode of an electron discharge tube establishes an anode-cathode discharge path for the tube which, being normally conductive in the idle condition of the repeater with both of the receiving relays in the marking condition, holds inactive a startstop oscillator. `Upon operation of either `receiving relay Yto spacing in response toV a spacing signal as, for example, the start impulse'of'startstop telegraph signals, the anode circuitof the discharge tube ris interrupted, quenching the tube, and either-,of two parallel paths is 'come pleted from the positive batterymto ,potential dividers associated with `thegrids of vindividual gas-filled electron discharge tubes having the operating windings ofthe transmitting vrelays connected in their anode circuits. The co`nnec. tion of the positive batteryl `to veither of. the potential dividers providesa 'preparatory grid biasingv .condition for its associated tube and the relation-k ships are such that either receivingrelay, upon operating to spacing, preparatorily biases the grid of the tube associated with the transmitting relay on the opposite side of the repeater.

vWhen the rst-,mentioned tube becomes deactivated the oscillator breaks into oscillation Aand oscillates at a frequency of one cycle per impulse interval of vcorrectly timed telegraph signals, and a detector circuit derives timing impulses at the rate of one impulse per cycle. These impulses are applied to the control grids of the electron discharge tubes associated with the operating windings of the transmitting relays. The timing impulse Vrenders conductive Whichever ofthe last-mentioned electron discharge tubes that was preparatorily biased by the receiving relay on the opposite side of the repeater,

'and the. tube, upon becoming conductive, operates its associated transmitting relay to spacing, thereby initiatingthe retransmission of a spacing signal over the other telegraph line. The impulsesapplied to the transmitting control tubes by'fthe detector circuit are of momentary duration but since the tubes are gas-lilled tubes the activated tube remains conductive and continues the retransmission of the spacing signal.

In addition to the anode circuit for the oscillator control tube, the previously mentioned series.v circuit from the positive battery to the armature and marking contacts of the receiving relays provides an anode circuit for a pair of gasiilled electron discharge tubes each of which has its-'cathode connected to .the cathode of oney of the transmitting control tubes and to a potential divider. In vthe idle condition of the repeater the pair bf `tubes connected-to the series circuit is normally conductive along with the oscillator control tube, and upon the operation ofeither receiving -relay l to' spacing they are quenched along'with the oscillator control tube. The tubesv of the vpair are always preparatorilybiased and their 'control grids receive a pulse from the detector circuit at the samev timeA as the transmitting `control tubes. However,v at the time ofv activationof. either of the transmitting control tubes d ue to the response of a receiving relayv to a'spacing signal the tubes ofthe pair cannot be activated because their common' anode circuit is 29 open at the marking contact of the receiving relay which is operated to spacing.

Upon the appiication of the next timing pulse to the control grids of the transmitting control tubes and to the grids of the pair of tubes, if the receiving relay which had been operated to spacing has returned to marking in response to a marking signal as, for example, the rst significant impulse of a telegraph code combination, the common anode circuit of the pair of tubes will have been reestablished through the series circuit and the preparatory bias will have been removed from the control grid of the transmitting control tube which is then conductive, and the pair of tubes will be reactivated. As a result of the reestablishment of a ow of current through the pair of tubes from the potential divider associated with their cathodes, those cathodes undergo a rise in potential and the cathodes of the transmitting control tubes, being connected to the cathodes of the pair of tubes, undergo a correspending rise. In the case of the transmitting control tube which is conductive the rise in cath-- ode potential decreases the anode-to-cathode potential difference in that tube below the discharge sustaining potential and therebi7 quenches th-e tube, permitting the associated transmitting relay to return marking to retransmit the marking impulse.

If the receiving relay hasnot returned to marking when the next timing impulse isv applied to the pair of tubes, their common anode circuit will be open, they cannot be activated, the potential of the cathode of the transmitting control tube which is conductive' will remain unchanged and the tube will remain conductive, continuing the transmission of a spacing impulse, which may be the rst significant impulse of a telegraph code combination.

The oscillator control tube has its control grid connected to receive timing pulses from the detector circuit along'with the previously mentioned tubes. Its control grid is always preparatorily biased so that each time'its controlgrid receives an impulse and the receiving relays Aare both in the marking condition, the tube will be reactivated. Thecontrol of the oscillator circuit by the oscillator control tube -is indirect, there being a timing 'circuit including electron ydischarge tubes and a condenser timing circuit interposed between them. Each-time the oscillator control tube is reactivated it seeks t cause the timing circuit to stop 'the oscillator. However, the timing circuit cannot be caused to stop theoscillator until an interval equal to that occupied by a start-stop telegraph signal-combination has elapsed following the starting of the oscillator. Accordingly, the timing'circuit 'does not become prepared to 'cause the stopping of the oscillator'until aboutthe time tha-t the'stoplimpulse of a telegraph code combination is received. At the time'that the timingfcircuit does become prepared to stop the oscillator, if the oscillator control tube is then conductive, the oscillator will be stopped. If the oscillator control tube has not yet become conductive and is awaiting the detector impulse pertaining to the stop impulse of the telegraph signal combinationat the time that the timing'circuit becomes prepared to ystop the oscillator, the oscillator will not be affected. Upon the activation of the oscillator control tube in response to the timing pulse pertaining to the' stop impulse of the telegraphsignals the timing` circuit will be causedto stop the oscillator., lit` will be apparent from 'the foregoing that the two Way repeater corresponding to this embodiment of the invention includes only four electromagnetic relays, namely, the two receiving relays and the two transmitting relays, and that all timing operations and all selecting operationspertaining to the retransmission of marking and spacing impulses are performed by electron discharge tubes.

ln accordance with another embodiment of the invention the electromagnetic transmitting relays are omitted and in their stead vacuum tubes are employed, one in place of each transmitting relay, the telegraph Vline terminating loop including theoperating windings of thereceiving relays and the anode-cathode discharge paths of the vacuum tubes. Normally, and in the idle condition of the repeater the vacuum tubes included inthe line circuit are biased for conductivity and current ows, representing a marking condition and maintaining the receiving relays operated to their marking contacts. When either receiving relay responds to a spacing signal, such as the start impulse of a telegraph code combination, which is represented by opening of the telegraph line at the remote transmitting station, the receiving relay operates to spacing and the current through the associated vacuum tube which replaces the electromagnetic transmitting relay is cut off.

Theimpulse selecting, impulse timing 'and character timing operations are performed by the same arrangement of oscillator, detector, oscillator control tube and character timing circuit and ransmitting control Vtubes as in the4 previously described embodiment. 'The spacing transmitting control tubes `have their anodes associated with potential dividers 'and connected to the control grids of the vacuum tubes which have been substitutedfor the electromagnetic transmitting relay. Upon the activation of either one of the spacing transmitting control tubes, it biases the grid of the associated vacuum tube in the telegraph line terminating` loop to cubani/thereby effecting the transmission of a spacing impulse in all respects comparable with the opening of the loop bythe armature of the transmitting relay in the previously described embodiment of the invention. Upon the activation ofthe pair of tubes having the common series circuit associated with their` anodes, they quench whichever ofthe spacing signal transmitting `control tubes that is .thenconductiva thereby restoring the cut-off vacuum tube to conductive condition and effecting the retransmission of a marking impulse. Itvwill be` noted that in this embodiment of the invention only two electromagnetic relays `are employed,` namely, the receiving relays, all impulse selecting, impulse timing and character timingl operations and also thespacing impulse transmitting operations being performed byelectron discharge tubes.

For a complete understanding of the invention reference may be hadto the following detailed description to be, interpreted in the light of the accompanying drawings wherein:

`lig. 1 is a vschematic circuit diagram showing one embodiment of the invention; and

Fig. 2 is a schematic` circuit diagram showing another embodiment of the invention.

Referring now .to the drawings and particularly tov Fig.` l, a telegraph linecomprising conductors Il and l2 extends to a remote ytelegraph station (not shown) at which the telegraph signaling battery is located.; Conductor H of the line terminates inthe regenerative repeater at the` marking contact of a transmitting relay I3 and conductor I2 `extends through the operating Winding ofl a receiving relay I4 tothevarmature 'of transmitting relay I3. When thejline comprising conductors II and I2 isclosed atthe remote station through vthe signaling battery, current in" the operating winding of relay-holds thev armature on the marking contact. The biasing winding of relay I4, which is the `lowermost winding, has one4 Vterminal l, connected to ground' and .the .other terminal ,o jconnected through resistor, I 6 to `j the anode of an electron' dischargetube 'I1 and to' a potential divider comprising-resistors I8' and I9 and battery 2 I. Tube `I1 is preferablyla gas-filled tube and inthe idle condition' of -the-repeateris cut oi. The potential divider underpthis condition of tube I1 provides a flow of current for the biasing winding of relay I4 seeking to drive the armature to spacing, but the-operating winding of `the 'relay dominates-.and holds the armature on the 'marking contact; --Themiddle winding of receiving relay-I4 is a holding windingfand has oneterminal connected to *grfound and the other terminal. connected through resistor22 Aand varistor or unidirectional conducting device 23 to the anode of tube I1'A andi-,tofthe potential divider comprising resistors I8 and I9, andthe junction of resistor 22 and varistor-23 is connected to one terminal of condenser'24, the 'other' terminal of which is grounded.`4 pvt; "zu: l

' The opposite line.-circuit',`: over' wlxichsignals received on the line circuit comprising conductors II and I2 are adapted to berepeatedcomprises conductors 3I and 32whichextend to a remote telegraph station at which the battery for supplying signaling current is located. Conductor 3l terminates in the repeaterfy at themarking contactofntransmitting relay 33 and conductor 32 extends through the operatingfwinding of a receivingrelay 34'to the armaturefof transmitting relay 33. lThe biasing winding,"iwhi'chv is tlie` lowermost winding,'of relay 34 is connected through resistor 36 to the anode of an electron discharge tube 31, whichvmay be like the tube' I1, and 'to a potential divider comprising resistors 38 and-39 and battery 4I. -The holding'winding of relay 34, Whichis the middle' winding, is connected' through resistor 42 and varistor 43 to the anode of tube 31 and to the potential divider comprising resistors 38 and 39, and'the'junction of resistor 42 and varistor 43 isconnected to one terminal 'of condenser '44, (the other terminal vof which is connected to ground.

With the repeaterl in the normal vidle condi#` tion, relays I4 and 34 being 'o'perfatedfto mark# ing, a circuit is tracedfrorn' the positive terminal of battery I, armature and marking' contactof relay I4, conductor 52,*ar1nature andl marking contact of relay 34, to branching paths, one` of which extends through conductor 53 to"the anode of electron discharge tube 54", Which'ispreferably a gas-filled tube and the-` otherl of which extends through conductorl 56 to th'eano'des of tubes,l 5 1 and 58 through load resistors 59?andY II'res'pec-v tively. Tubes 51 and 58 are preferably of the same type as tubes I1, `31.and54; jfAt this time tubes 51, 58 and 54 are conductive.v .Noyspecial importance attachesto thefact thatltubes 51 and 58 are conductive but `tube, 54'maintains the' imf pulse and character timing circuits dormant.v

The cathode of tube 54 is connected to apo-` tential divider comprising resistors' 62 l.and3 and battery 64` which has its ,positive terminal.

grounded. It is ajcharacteristic',.orgels-filled tubes that when they are" conductive Vthel cathode" is less positive than the anode by only a'small potential difference. The cathode of tubel 5411s also connected by conductor 66 to the anode of a gas-filled electron discharge tube 61. Accordingly, the anode of tube 61 is only v slightly less positive than the anode of tubev54. The cathode of tube 61, which is conductive at this time, is connected to the junction of resistors 68 and 69 which are connected in series between negative battery 1I and ground. Thev tube 61 has a low and substantially constant anode to cathode voltage drop when conductive and the values of resistors 68 and 69 are such that thecathode is slightly positive with respect to ground.

The control grid of a tube 12, which is similar to tube 61, is connected to the cathode of tube 61 through resistor 13. The control grid of the lefthand triode section of a twin triode `electron discharge tube 14, which is preferably a vacuum tube, is also connected tothe cathode of tube 61 through a resistor 16. The cathode of tube 12 is connected to the junction of resistors 11 and 18 connected in series with resistor 19 between nega-n tive battery and ground. The anodeof tube 12 is connected through variable resistor 8| to thev junction of resistors 18 and 19. A condenser 82 is connected between the anode of tube 12 'and the cathode of tube 61. ,I y

' Since the cathode of tube .61l is slightly pos' itive with respect to ground as previously stated. the grid of tube 12 is also slightly positive with respect to ground. The cathode of tube 12 is negative with respect to ground by virtue of the potential divider comprising resistors 11, 18 and 'I9, so that the control grid of tube 12 is pos-L itive with respect to the cathode and the tube is conductive. Resistor 8i is of high value, so that only a very small current is drawn by tube 12; Condenser 82 is charged to the difference in po` tential between the cathode of tube 61 and the anode of tube 12 and the charge on the condenser is positive on the left-hand plate by virtue of the fact that the cathode or tube 61 is slightly positive with respect to ground and negative 'on the right-hand plate by virtue of the fact that the anode of tube 12 is negative with respect to ground by the potential diierence across resistor 19 and the potential difference across variable resistor 8I due to the anode current through the tube.

The cathode of the'left-hand triode sectionof tube 14 is connected to the junction of resistors 85 4and 81, connected in series between negative battery 88 and ground. Accordingly, the cathode of the left-hand triode section of tube 14 is negative with respect to ground. The grid of the, left-hand triode section of tube 14 is positive with respect to ground by virtue of its connection to the cathode of tube 61. It follows that the grid to cathode potential is such as to render the leithand triode section of the tube conducting. The left-hand anode is connected through conductor 89 and winding of tapped inductance 9| to ground. Since the left-handtriode section of tube 14 is conductive, a steady direct current flows in inductance 9|. The inductance is shunte'd by a condenser '92, and the inductance and condenser together form an oscillatory circuit which is held in a non-oscillating condition byithe directeur-l rent through the inductance winding `9i, with a small charge on condenser 92 equal to the ohmic potential difference across inductance!) I, and with energy stored in the magnetic field produced by .the steady direct current through the. indufct,l

ance winding. The upperterminal of inductance 7, Winding 9| .is connected through resistor 33 to the grid of the right-hand triode section of tube lli. The-tap terminal of inductance winding ci is connected through variable resistor Slt to the cathode of the right-hand triode section of tube 14. yThe grid is also connected to the tap terminal of inductance winding 9| through resistor 25. These elements comprising inductance winding Si condenser 32 and the right-hand triode section of tube 'HL-and their interconnections, will be recognized as an electron tube oscillator circuit. The condenser 92 is prei'erably adjusted so that the frequency of the oscillator is twice the tele graph signaling frequency, from which it follows that the duration of each cycle of th=` oscillator is equal to the duration or one impulse of correctly timed telegraph signals. The anode oi the rightmhand tricde section of tube 1d is connected to positive battery 91.

The upper terminal of inductance winding Si is slightly negative with respect to ground by the amount of the steady pctential diierenee across the inductance winding. This negative point connected through resistor to the grids oi both. triode sections of a twin triode tube 99 which is preferably a vacuum tube, The cathodes of tube 99 are connected to the movable contacto-r ci the potentiometer Iii! connected between positive and negative batteries |82 and |53 respectively. The left-hand anode of tube 9d is connected through resistor |64 to positive battery itil and the right-hand anode of tube Sli is connected through resistor |51 to positive battery |38. With the grids of tube 99 slightly negative witherespect to the cathodes, there may be a smali discharge current flowing in both halves oi the tube and, therefore, the current flowing through resistors |54 and |01 may cause the anodes ci the tube to be slightly less positive than the full potential of batteries |66 and lill'. The left-hand anode of tube 99 is connected through condenser III to the grid of a gas-lled electron discharge tube ||2 which may be similar to the tubes l1, 51, 5B, 31, 54, 61 and 12. The same anode is also connected through condenser ||3 to the control grid of tubes 51 and 58. The cathodes of tubes I1, 51 and ||2 are connected to the junction of resistors i4 and H6 connected in series between negative battery I1 and ground, The righthand anode of tube 99 is connected through condenser I8 to the control grid of an electron discharge tube ||9 which is preferably gas-filled and may be of the same type as the others hereinbeforev described. The cathodes of tubes 58, I3

and 31 are connected to the junction of resistors I2| and |22 connected in series between negative battery |23 and ground. The right-hand anode of tube 99 is also connected through condenser |24 to the grid of tube 54.

tubes 51 and 58 is supplied from the junction of F resistors |4| and |42 connected in series between negative battery |43 and ground. Biasing potential for tube I I9 is supplied from the junction of resistors |46 and |41 connected in series with resistor |48 between negative battery |49 and coA ground. Anode potential for. tube ||9 is supplied from the junction ofiresistors |5| and |52 connected in series between positive battery |53 and ground.. Biasing potential for tube 31 is supplied from the junction of resistors |56 and |51 connected in series with resistor |58j between neg ative battery i513y and ground. Biasing potential for tube 54 is supplied fromthe junction of ref sistors |5| i and |52 connected inseries between negative battery |53 and ground.

In the idle condition of the repeater, thecondition of the gas-filled tubes is as follows:

Tube I1quenched Tube 61`conductive Tube 31-quenched Tube 12-conductive Tube 54-conductive Tube IIZ--quenched Tube 51-conductive Tube IIS- quenched Tube 58-conductive It will be assumedthat start-stop permutation code signals begin to be received by the repeater from the line circuit comprising conductors and |2-tc be repeated in the line circuit'v comprising conductors 3 I' and'32. The start impulse of the first permutation code signal combination is of spacing nature and causes the armatureof receiving relay I4 to travel from the marking to the spacing contact. The armature, upon leaving the marking contact, disconnects battery 5| from the circuit previously traced over conductor 52, the armature and marking contact of receiv` ing relay 34, conductor 53 to the anode of tube 54 and conductor to the anode of tubes 51 and ,58.1 These tubes, having their anode potential thus disconnected are quenched. With tube 54 i quenched, its cathode immediately goes to a more negative potentialthan it had when the tube was conductive and carries the anode of tube 61 more negative to a value below the discharge sustaining potential of tube 61 and this tube likewise becomes quenched. With tube 61 quenched, the

potential of the cathode drops abruptly to that maintained by the potentiometer comprising resistors 68 and 69 and battery 1|. The control grid of tube 12 and the grid of the left-hand triode section of'tube 14 will undergo a corresponding drop in potential'and; in the case of tube 12, the new grid potential is below the ring potential. The abrupt decrease in the potential of the cathode of tube 61 causes a negative pulse to be impressed through condenser 82 on the anode of tube 12, reducing the anode potential below the discharge sustaining potential and thus cutting off this tube. None of the gas-filled tubes is now conducting. Intthe case of the left-hand triode section of vacuum tube 14, the lnew grid potential is below the cut-off potential `of the tubeso that theilow of direct current through the anode-cathode circuit of this tube, which includes inductance winding 9|, is interrupted.

Due principally to the energy stored in the magnetic eld of inductance 9| and also to a small extent to the charge on condenser 92, this circuit begins to oscillate at a frequency of one cycle per impulse interval of telegraphl signals and oscillation at uniform amplitude is maintained by the right-hand triode section of tube 414. The grids of tube 99 are connected to the `sistor 8|. vcharacter timing operation as will be described 'i increasesand the anodes become less positive due land 58, tube I I9 and tube 54, thus decreasing the potential of these grids with respect to their cathodes. As the conductivity of lthe triode sections of tube 99 decreases inthe second half of i;

the positive half-cycle of oscillation of the oscillatory circuit the anodes of tube 99 swing `more positive in potential and positive pulses are impressed through condensers I I I, H3, IIB and |24 on the control grids of tubes H2, 51, 58 H9, and

54 momentarily carrying those grids above the ffconden'sers IH, I I3, lI I 8 and |24 by tube 99, the grids of tubes H2, 51, 58, H9 :and 54 are momen- .tarily made more positive with respect to their cathodes. Tube I I 2 cannot re because it has receivedI no preparatory bias through the spacing contact of receiving relay 34. Tubes 54, 51 and :58 cannot fire because'their anode circuits are opened at themarking contact of receiving relay I4. Tube H9 is preparatorilyr biased and it fires. In the same manner that tube 31 reversed the ,ilow of current'throug'h the biasing winding of -relay 34, tube II9 reverses the flow of current through the winding of Vtransmitting relay 33,

' causing that relay vto move its armature away ring potential with'zrespect to their cathodes.

This occurs on'ce for each cycle of oscillation of the oscillatory circuit.

In the meantime condensery 82, having applied, to its'left-hand plate the reduced potentialof the cathode of tube 61, discharges. The discharging circuit includes high variable resistor 8| so that the discharging ofthe condenseris slow and is adjustable by means of variable re- The discharging of condenser 8.2 is a later.

Returning again to 'consideration of relay I4, whenv the armature reaches the spacing contacts it completes a conductive path from battery 5I over conductor |66-to branching paths` one Aex- Y tending through conductor I 91 and resistor yI 68 to the junction of resistors |51 and |58 and the other extending through conductor |69 and resis'tor |1| to the junction of resistors |41 and |48. The connection of positive battery 5I to these potential divider junction points results inV raising the potentials of the control grids of4 tubes H9 and 31 relative to their cathodes. In the case of tube H9 the new potential of thecontrol grid is still below the firing potential, so that tube rI I9 does not nre.

In the case of tube 31, the new potential is above the firing potential and the tube lires. Due to theow ofdischarge current through tube 31 from the potential divider comprising resistors 38 and 39, the

anode of the tube swings from a positive to a negative potential relative to ground. This reverses the vflow of current in the biasing winding of receiving relay 34, changing the bias condition from a spacing to a marking bias. This is in preparation for the operation of transmitting relay 33 which, upon being operated to spacing for the retransmissionof the spacing impulse, in-

terrupts the flow ofcurrent through the operating winding of relay 34, which would operate its armature to spacing were it not for the reversal 'of the current through the biasing winding, thereby seeking to repeat back to the line circuit comprising conductors II and I2 the spacing impulse 'received by relay I4 from that line circuit. AThe relatively negative potential on the anode of tube 31 is at the polarity from the standpoint of v aristor 43 which causes it to pass current in:

'its forward direction and this current flows to charge condenser 44 in preparation for energiza- `tion of the middle or locking winding in the marking direction. As the condenser becomes Icharged currentwill also flow through resistor 42y and the middle or locking winding ofV relay 34 in the marking direction thus aiding the lower- -mo'st or biasing winding now conducting current in the marking direction.

When the iirst positive pulse is impressed oni from the marking contact, thereby opening the terminating loop of the line circuit comprising It will be understood that transmitting relay 33, and also transmitting relay I3, could be a neutral relay instead of a polarrelay, -or could vbe a spring biased polar relay. Under these circumstances, and with reference to relay 33, a poftentiometer and battery combination adjusted to provide substantially the same potential as that at the anode of tube H9 may be substituted for the ground connection to the relay.l Under these circumstances relay 33 would normally be deenergized. Upon the activation of tube H9 accompanied by the swinging of its anode from positive to negative with respect to ground, relay 33 would be energized to disengage its armature from the marking contact, thereby effecting the transmission of a spacing signal. l

During the transmission of the spacing impulse, the condition of the gas-lled tubes is as follows:

- Tube I1-quenched Tube ISI-quenched Tube 31-conductive Tube 12quenched Tube 54-quenched Tube II2-quenched lTube 51-quenched Tube IIB-conductive Tube 58-quenched f y It will be assumed that the first signicant im- ,pulse of,` the code combination, which is the iinpulse vfollowing the start impulse, is of marking nature. In response to this impulse, receiving relay I4 reoperates its armature from the spacing to the marking contact. As the armature leaves the spacing contact, it removes the preparatory bias from the control grid of tube v| I9 and the ring bias from the control grid of tube 31. The restoration of these tubes to their previous condition of bias .does not affect the conductivity of these tubes `because of theiry characteristics as gas-filled tubes that, having been kiired, they are no longer responsive to control by their con- 'trol grids and, accordingly, they remain conductive and maintain the marking condition of relay l34 and the spacing condition of relay 33. As the armatureoi receiving relay I4 reengages its marking contact, it reconnects battery`5| to they anodes of tubes 51, 58 and 54. The reconnection of anode potential to'theser tubes does not change their condition of non-conductivity because their control grids have only the normal bias which, as previously described, is below the firing potential of the control grid. l

One cycle of the oscillator circuit after the first positive impulse was impressed on condensers I I, II3,..I I8 and |24, another positive impulse is-impressed upon these condensers. The interval be- `.=twe'en the'two positive impulses is equal vto? one 11 through condenser III has no effect on tube. II2 because this tube is not preparatorily biased. The positive impulse through condenser IIB has no effect. on tubes H9 and 31 because they are already conductive. The positive impulse irnpressed on condenser |I3 raises the potential of the control grids of tubes 51 and 58 above the firing; potential and these tubes iire. The positive impulse impressed through condenser` |24 is momentarily applied to the control grid of tube- 54 and this tube res. By virtue of the low internal voltage drop in a gas-filled tube when conductive, the cathodes of tubes 51 and 58 abruptly rise to more positive potentials. The cathodes of tubes; H9 and 31 are connected to the cathode of tube 5,8 and they undergo a corresponding rise which, reduces the anode-to-.cathode potential in the tubes i I9 and 31 below the discharge. sustainius patential; quenching them.

Witl' i tube IIS quenched, its anode again assumes a positive potential with respect. to. ground, thereby restoring current in transmitting relay 33 in the marking direction and causing the armature to reengagel its marking contact for the retransmission of the marking impulse into the line circuit COmprising conductors. 3|. and 32. WithV tube 31 quenched, the anode of this tube now swings to a p ositive potential with respect toA ground thereby again reversing current thraugh the biasingl winding of receiving relay 34,v

which is the lowermost winding, and restoring the spacing bias to this relay. Current through var istorv 43 is interrupted but condenser 44 now discharges through resistor 42 and the locking winding oi receiving; relay 34 thereby maintaining Ya marking hold upon receiving relay 3.4 for an interval after the spacing bias has been restored in the biasing winding. The locking of the receiving relay 34 in markingI condition for this additional interval assures that conditions in the repeater shall become stabilized before the normal sensitivity of relay 34 to spacing impulses is restored. One of the reasons that, this precaution 1S. desirable. is that the restoration of spacing bias in the receiving relay 34 and the restoration of marking current in the transmitting relay 33 occur substantially simultaneously due to the simultaneous quenching of tubes I i9 and 31. Until the relay 3,3 has actually operated its armature to the marking contact, the relay 34 is solely under the control of its locking and biasing windingy and inthe absence of the locking windingV or in the absence of the condenser 44 to prolong the locking condition, the biasing winding might operate relay 34 to spacing before the transmitting relay 33 had reclosed the loop circuit, vthereby quenching tubes 51, 58 and 54 and possibly interfering with the quenching and de ionization f tubes IIS and 31.

During the transmission of the marking impulse the condition of the gas-lled tubes is as follows:

VTube {T- quenched Tube I2- quenched Tube II2--quenched Tube IIS-quenched Tube Ile-.quenched Tube 3.1-quenched Tube 54-conductive Tube Eilconductive Tube 58-conductive control. of its grid which is negative with respect .to the cathode by virtue of the charge on condenser tZ which is in the process of leaking oil through variable resistor 8l. The values of condenser 82 and restor 8| are such that the control grid does not reach firing potential relative to the cathode until or, preferably, just before the time that the positive pulse pertaining to the stop impulse at the end of the permutation code combination is impressed on condensers tI I, |I3, H8 and |24.

The retransmission of the successive significant impulses of the code combination proceeds in the manner hereinbeiore described. When any spacing impulse follows a mark-ing impulse, tubes 5.1, 58 and 54 are quenched under the control of the armature of receiving relay I4, tube 31 is fired as soon as the armature reaches the spacing contact and tube IIQ is fired when the positive timing impulse is impressed on condenser II8. When a marking impulse follows a spacing impulse the anode circuits of tubes 51, 5 8. and 54 are reestablished under the control of the armature of receiving relay I4, and .when the positive timimpulse is` impressed on condenser H3, tubes 51 and 58 are red, quenching tubes IIS and' 31. At the same time tube 54 is red by the. positive impulse impressed on condenser |24. This is` an idle operation at this time, since tube. 54- cannot fire. tube 61. When a spacing impulse.. follows another spacing impulse no change in the condition of the repeater occurs as a result of the positive timing impulses impressed on eondensersv I I I, H3, IIS and |24 because the anode circuit of tubes 5l, 5.8 and 5,4 remains open at the marking contact of receiving relay I4, and since the tubes 5.1 and 58I cannot be fired under this condition the tubes I |18 and 3g1 remainy conductive. When a. markingI impulse follows another marking impulse no. change occurs in the repeater as a result of the: positive timing; impulse impressed on condensers` Ill, H3, |Ia8 and |24 because neither ofthe tubes I I 9 nor 31 is preparatorily biased for activation. and tubes 51 58 and, 54 are already conducting.

About the time, that, the. seventh positive impulse. is impressed upon condensers IH,y H3,4 H8 and |241, and preerabh/iust before this time, condenser 82 discharges to a.. level at which the controll iclpf' tube (il. is. at, such potential relative to; t. cathode as: tube capable of firing the tube. li' the last significant impulse of the code combination was @if marking nature, tube 54 is. conductive along with tubes 5l1l and Sii,4 and has: applied full positive potential to the anode of tube er so that tube el. will. fue as; soon as its Control grid reaches the proper potential under the control or condenser 82;A 1i the last significant impulse of the code combination hasy been oi spacing nature, tubes 51:, 58 and 54 simenon-conductive, tubes I. L9.: and 31 are conductive and tube 61 awaits the ring of tube 54 under the control of the, seventh positive; timing impulse., When tube Q9; impressesA this impulsel upon the condensers I II, I I3, I I'Band |24, tubes; 51 and- 58,:re, quenching tubes lilgilf and- Slf thereby initiatingthe transmission cf the stopl impulse. Tube 54; fires and from its; cathode provides positive potential for the.. anode.v oftube 5ft which in turn fires. Uponv ,the ring or tube 5l the, cathoder returns to its initialor steady state potential, slightly positive with respect to. ground, and impresses this potential through resistor 156 upon the grid of thev leithand triode section of tutu-eV 14. which again becomescenductive, providing a steady ow of current ,through inductance l,,win,cling 3| ,V thereby stopping [oscillationr of the o'I ator'y "c'irc'uitand suspending the' productie ff timing impulses; Thepositivepotentialbf `t cathode of t'ube |51 is also applied throu'ghgresistor'liftoi the control grid of tubev 12, biasing 'that"tub`e"toiirng condition. The positive potentialuflthe cathode of tube, 61 impressed 'onithejleft-'hand side fcon denser 482 causes a positive' pulseto betransmitted through the condenser vtofthe anode 4 of;.tu ];v e'12 causing that tube tov fire. ','Ifube 12,` provides a -10W impedance ypath by comparison fwith the `imped ance of .variable `resistorY 8| for recharging' condenser 82 and the condenser quickly recharges to It should be noted thatithe tube 5,4; leic'er'cising control'over the firing offtube 31,1assu're`s tlie'pro'- duction of the seventh y positi've'timing impulse, .if such impulse 'is needed;` andyitis iledd when' the last signiiicant impulsejofI the, telegraph 'signal combination isA of'spacinglnature to fire tubes 51 and 58 for the purposefj'of, quenching tubes I I8 and 31 thereby to .operate relayl 33 vjtov marking for the transmissionof thestop impulse. y,The seventh timingimpulse isnotespecially needed when the last significantirnpulse yof, the telegraph signal combination is yof marking nature,` because transmittingrelay `33 willbe operated to marking by the quenching, of tubes` l ISand 31kasT a're. sultl ofthe firing ofjtubes `51' andg58' for the last signiiicantimpulse of the codecombination, and as no spacing ysignal .normally intervenes ythe last'significantcodeimpulse andthe kstop impulse, relay 33 4will continuev inmarking u,conditionior transmission of the, stop'infipulse, Were it not for the ,provision oi'tube 54 ,to control 'tube 61 jointly, with condenser"82 itl would be necessaryto time the` discharging of' condenserfiso that it could not bringv the ygrid of tube 61'A to'activating potential until after thefoscillator vhad produced '14 winding of relay `I 4 and tube I I2, whenwred under the control of positive timingimpulsesthrough condenser |I|', operates the relay I3 to spacing. The operation of tubes 54, 61 and 12 starting and stopping the oscillator andtirning'the duration of the character, the operation of tube 14 asan oscillator and oscillator control and the opera-- tion of tube SQ as an impulse generator are the same for either direction of transmission through the repeater.l The repeater accommodates the transmission of break signals in either direction. For example,

, when permutation code signals are being .re-

transmitted into the line circuit comprising conductors 3| and 32 under the control of transmitting relay 33, a break signal may be transmitted by the station which is receivingv the signals by the opening at that station of theline circuit comprising conductors3| and 32. If the break signal is initiated at an instant that transmitting relay 33 is transmitting a spacing signal, the line circuit comprising conductors 3| and 32 will be open at the marking contact of relay 33, and the opening oftheline circuit at the remote station will have no eiiect on receiving relay 34 which is held to marking by the marking current in the biasing winding. As long as spacing impulses are received by receiving relay I4 transmitting relay l33 will be operated to spacing and the break signal will have no effect. In response to the first .marking signal received by relay I4. which may be the stop impulse or one of the signicant impulses of the code combination, and

upon the generation of the positive timing imseven full cycles and tube, 89 had produced seven positive timing impulses and the vtiming of the condenser dischargingcircuit might therebybe much more critical4 than' snecessary with the dual control over tube 61. y

When the transmission of signals-is yinthe opposite direction from the "line" circuit comprising conductors 3| and 32'to the line lcircuit comprising conductors I"|I and I2 thel operation vof the repeater is the sarnefwith theeXception-'that tubes I 1 and I I2 are employedfor controlling the Vtrans` mission of spacing signals instead-ofthe tubes 31 and i9. The armature 1f-'receiving relay 34 interrupts the anode circuit of` tubes 51, 58 and 54 at its marking contact and provides the jpreparatory grid bias for tube 2- and fthfiring 'grid' potential for tube l1 throughfitsarmature" and spacing contact, conductor |1|5 ,'`conductorY |11 and resistor `A|18 'to the junction of resistors |32 and I 33 in the case of tube I I2 and conductor |13 and resistor I3|to the" junction ofresistors |21 and |28 in the c'ase of "tube A|15."v 'Tuben provides pulse pertaining to that telegraph signal impulse, relay 33 will be restoredto markingv and ythe marking .bias on relay 34 will be replaced by 4a spacing bias. However, relay 31|.Wil1 not'respond to the break signal and operate its armature to spacing until the marking hold effected by the discharging of condenser 44 through the locking Winding of relay 34 has been dissipated by the discharging of the condenser. Thereupon, receiving relay 34 will operate its armature to spacing, quench tubes 51,58 and 54, operate tube I1 to place a marking bias on receiving relay I4, preparatorily bias tube I|2, and upon the generation of the next timing impulse tube H2 will rire and repeat, the break signal to the line, cirl' cuit comprising conductors |I and I2. As long as relay34 receives the break signal, transmitting relay i3 will remain operated to spacing, tube 54 will be prevented from rlringtube 6.1"yvillhbe,`

prevented from' ring, although condenser "82 will undoubtedly time outand bias tube 61"f o r.

tubes 51, 58v'and 54vioractivation and in response to the next positive vtiming impulse, these 'tubes Will be `lred, tube 51,v will fquench ,tubesIT and ll'z and-'tube 54Wi1i causetube `s1 to fire wenn in turn Will 'stop the oscillator and suspend the generation of the ztimingim-pulses.

By Way of completing the, description o ffth'le' embodimentof,k the invention shown in Fig."- l, attentionisfdirected to two features.

vides for adjustment ofthe character4 timing function performedby condenser 82 in Acooperation with variable resistor 8|. Thedischarginglf time of condenser82 may be increasedv or de creased' byy increasing or decreasing" the', effec resistance 'of variableuresistor" I.

y Onejof' these features is ,that the variable resistor 8| pro--` asignar the variable resistor the time interval between the quenching of tubes Sl in response to a start impulse of telegraph signals and the arrival of the control grid of tube 51 at a potential relative to the cathode which represents the lactHating condition of the tube may be adjusted within close limits. lThe other feature is the relation of potential divider 50| to the impulse generating tube 99. The potential divider l0! provides an orientation adjustment whereby the time of production of the rst positive timing impulse and each succeedingjtiming impulse may be advanced ordelayed Vrelatiye to the start impulse of received telegraph signals in order to adapt the repeater to various ,conditions of bias and' distortion in received signals, so that the timing impulses shall be produced relative to the ren ceived telegraph" impulses` when the receiving lrelay is responding to the most eiective `part of each received telegraph impulse. Since the time of occurrence of each positive timing impulse is the time at which the repeater selects between marking and spacing impulse transmission under the control of the receiving relay, theY selecting instants may be adjusted by means of potentiometer i 0| to the particular'condition of the signals being received.

The embodiment of the invention shown in Fig. 2 differs from that shown in Fig. l' principally in the termination of the telegraph loop circuit in the repeater and in the resultant signal transu mitting arrangement. The oscillator, oscillator control and timing impulse producing circuits in Fig. 2 are identical with `those in Fig. l. Likcwise, the start-stop control circuit char-- acterV timing circuits are the same in both ngures. Gas tubes in like number and function for marl; ing and spacing selectionr and for receiving relay biasing and lockingV are employed in both figures. For the sake simplicity these principal' com'- ponents have been identified by the same reference numerals in Fig.2` as in Fig. l. ln those instances in which the two figures difer signincantly as, for example, in the case of' entirely different components and different potentiall supply arrangements, new and different reference characters have been applied in- Fig. 2, and these reference numerals are all inthe 209 series.

One of the line circuits entering thel repeater comprises the line conductors 2 Il and. 2 I2. Conductor 2l terminates .at the cathode of an electron discharge tube which is preferably a vacuum tube. Conductor 2'|'| is also grounded at the repeater for the purpose of providing a reference potential of thev cathode to which the control grid of tube 20|" may be related to prevent the potential of the cathode from varying with respect to certain operating potentials applied to the grid of the tube.v The cathode of the tube being connected tothe end of. a telegraph line conductor, such variation might result from line leakage resistance and other factors. Line conductor 2I2 extends; through the operating, winding of receiving relay I4 and terminatesV at. the anode of vacuum tube 20|.. Receivingl relay I4 is` provided with biasing and: locking windings associated with the anode of gas-illedv tubey il as in Fig. l. The control grid of tubeA 20|. is connected to the anode of ga's-lledtube ||"2-. The anode of tube ||2 is also connected' to two po tentiometer circuits, one connection being to the junction of resistors 202 and 203 connectedY inv series between positiveA battery 204 `and ground andl the other connection being to. the junction ofv resistors 206 and 201V connected in series between'negative'battery 200 and ground. These potentiometers provide a grid potential for tube 20|, in the idleor marking condition of the line circuit comprising conductors 2| I and 2|12, such that current flows'v inthe line circuit to operate receiving relay I4to lits marking contact. As in the foregoing table of conditions of the gas-filled tubes for the idle or marking condition of the repeater, tube `|`|2 is non-conductive, so that the potential of the grid of tube 20| is determined solely by the two potential dividers to which it i`s connected. It may be assumed that the grid of tube 20| is at or above ground potential to provide the necessary flow of current in tube 20| and accordingly the anode of tube I|2 is at the same potential. TheA potential divider comprisingjresistors I |4 and |`|6 from which the cathode of tube |I2 receives yits operating. potential has associated therewith the negative battery Ill., as previously described, so that the cathode of tube I|2 is negative with respect to the anode by a sucient amount 'that when, at the proper time, a potential is applied to the grid of tube I I2 to cause it to re, the tube Will nre.`

The biasing arrangement for tubes ||2 and in Fig. is' slightly different from that disclosed in Fig. 1.; A conductive path is traced from negative battery 2l6`through resistors 2`I'|, 2|8 and 2|9 in series to ground and the grid of tube |I2 is connected to the junction of resistors 2|8 and 2|9. From the junction of resistors 2|'| and 2| 8, resistors 22| land 222 are connected in series to ground yand the grid of tube I'I is connected to the junction of resistors 22| and 222. Conductor |16 which extends from the spacing contact of receiving relay 34 is connected through a single resistor 223 tothe junction of resistors 2|?, 2`|8 and 22| and positive potential is supplied over conductor |16 when the armature of relay 34 operates to spacing and applies to the controll gridof tube. a potentialrelative to. the cathode ofi that tube suflicient to nre the tube immediately, and applies to the control grid of the tube ||2 a preparatory bias.

At the opposite side of the repeater the incoming line conductor 23| is grounded and terminates at the cathode of a vacuum tube 226. The line conductor 232 extends through the operating winding` ofreceiving relay 34 and terminates at the anode of vacuum` tube 226. The grid of the tube is .connected to the anode of gas-filled tube IIS, to thejunction of resistors 221 and-.228, connected in series between ground and positive battery 229 and to the junction of resistors 236 and 231 connected in series lbetween negative battery 238 andground. The biasing arrangement for tubesl.3'| and I I9 is the same as that for tubes I 'I and ||2 in Fig.. 2. Resistors 24|, 242 and243 are connected in series between negative battery 244 and ground andy the control grid of tube II-9 is connected to the junction of resistors 242 and 243.* Resistors 246 andy '241 are connected in series-between the junction of resistors 24| and 242 and ground, and the control grid of tube3`| is connected to the junction of resistors 246 and 241. The spacing contact of receiving relay I4 is connected through conductor |65 and resistor 248 tothe junction of resistors 214|, 242 and 246. l y v In the operation ofA therepeater to transmit signals receivednover. the line circuit comprising conductors2| and 2 I2 into the line circuit comprising conductors 23| vand v232., the start impulse of. af permutation signal code combination is of spacing nature and is represented by opening of l 1 s the line circuit at the` transmitting station. The effect of this to open the anode-cathode discharge path of vacuum-tube 20| and relay I4 operates itsl armature to spacing underthe control of its biasing winding. In the manner described in connection with Fig. 1, tubes 51, 58, 54,v Bland I2 are-quenched and the oscillator is started-as a result o f departure of the armature of relay I4 from the'marking contact. With the armaturevin engagement'with the spacing contact, the grid oftube'3l is immediately vbrought to firing potentialand'thetube fires to .hold receiving relay 34.in the marking condition.. lTube II9 is at the same time preparatorily `biased for operation.; When tube 99 supplies the rst positive timing impulse, tube II9 lires yand its anode assumes a Aless i positive potential than ,it has in the steady state .'condition,` carrying vthe grid of tube 226 to cutroif potential and thereby cuttingv off current through tube 226. Thus current is cut off in the=line circuit comprisingyzconductors 23I and 232 whichisthe spacing condition of the line. The repeater remains in this condition as long as 'receivingrelay I4 vresponds tov a spacing signal.. When the receivingv relay I4 is restored to marking condition vin response to a marking signal, preparatory Abias `is removed. from the control grid oftube II9,vthe operating bias is removed from'the control grid yof tube-31 and the anode: circuitof tubes-51, 58and 54 is reestablished. Uponitheproduction of the next'` positive timinglimpulse by tube 99 following the restorationv of receiving relay I4 to marking, tubes 51, 58 and 54 arerered., Tube 58 quenches tubes 31 and I I9, theformer restoring the spacing bias to receiving relay 34 'and the latter restoring the gridof tube 226 to its initial value permitting line current to ow in the linecircuit comprising conductors 23I and 232. Aboutfthe time that the stop impulse` is.r received, condenser 812 times out and conditions tubetl for ring. If tube 54 is then conductive or when it is rendered conductive in responseto the stopirnpulse, tube 61 fires, in turn ringtube 12an d suspending opera.

tion ofthe oscillatorthrough the leftrhand triode section of tube 14. From the foregoing it vwill e apparent that the principal difference b etweenthe embodiment of the invention shown in ;Fig. .2 and that shown in-Fig. 1 is thesubstitution of vacuum tubes for electromagnetic relaysastransmitters of startstop permutation code signals. All functions and operations'areperformed by electron discharge instrumentalities withtheexception of the signal receiving operations which are performed by electromagnetic 4relays y The impulse timing, circuit including the oscillator and detector, charactertiming circuit-including the startstop oscillator control circuit disclosed in identical form in Figs. 1 and 2, are similar to impulse and character timing circuits 2,476,864, patented July 19, 1949, by E. B .-Hearn and J. A. Krecek. Although specific embodiments of vthe invention have been shown in the 4drawings and `de-V scribed inthe foregoing specification, it `will be.

understood that the invention is notlimitedto v such specific embodiments but is capable of modification andl rearrangement without departing from the spirit of the invention andv within the Loi.

" of timing impulses and said receiving relay upon response thereof to a spacing signal for reversely.

transmitting relay associated therewith, a source of timing-impulses, a gasr-iilled electron dischargetube having its anode connected to ,the transmitting relay associatedwith one of saidv c eiving relay, a ltransmitting relay, ay source if of timing impulses, a gas-filled electron discharge tube controllable jointly by said source of timing impulses and said receiving relay upon response thereof to a spacing signal for operating said transmitting relay to spacing, and a gas-lled.

2. In a. regenerativetelegraph repeater, a

receiving relay, a transmitting relay having a f single winding normally energized to transmit a marking signal and v reversely4 `energizableI ,to transmit -a spacingrsignal, means including a source oftiming impulses, a gas-filled electron discharge tube controllable jointly by said source energizing said transmitting relayto effect transmission of a spacing signal, and a gas-lled .electron 'discharge tube controllable jointly bysaidsource oftiming impulses and said receiving relay upon response to a marking s ignalforquenching saidV first-mentioned tube to,r effect reenergizationj of said transmitting relay for vtransmission of a marking signal. I i 3. In a regenerative telegraph repeater,l aflrst telegraph line having a receiving relay and a transmitting relay associated therewith, a second telegraph line having a receiving relay and a transmittingrelay associated therewith, a source of timing impulses, a gas-lled electron discharge.

tube operable jointly by said source of timing imn pulses and one of said receiving relays upon response thereof to a spacing signal received over its associated line for operating the transmitting relay associated with the other line to spacing condition, and a gas-filled electron discharge tube operable jointly by said one receiving relay upon response thereof to a marking signal and inder pendent of said transmitting relay associated with the other line for quenching the first-mentioned tube to restore the transmittingrelay associatedl with said other line to marking condition solely as a result of said quenching.

4. Ina regenerative telegraph repeater, a rst telegraph line having a receiving relay and a transmitting relay associated therewith, a second telegraphline having a receiving relay and a lines and operable jointly by said source of timing impulses andthe receiving relay associated with the other line for operating the transmitting relayf associated with said one line to spacing condition, a gas-filled electron discharge tube having its anode connected to a winding ofv the: receiying` relay associated with said one line and operable l by the receiving relay associated with said other. line for holding the receiving relay associated with said one line in marking condition, and a gas-lled electron discharge tubeoperable jointly by said source of timing impulses andthe receiving. relay associated with said other line uponrresponse thereof to a Imarking. signal for quenching said rst-mentioned. and said. secondmentioned electron discharge tubes to restore the transmitting relay asscciatedwith .Saidpne im@ tc marking condition and to release the marking hold on'` the receiving relayassociatedwith the same line. y

5.- In a regenerativetelegraph repeater, a rst telegraph line having a. receiving rela-y and a transmitting relay :associated therewith, a sec--v ond vline having a receiving relay and atransmitting relay associated therewith, a gas-nlled' elec-- trondischarge tube'v individual to eachtransmitting relay :and having its anode connected-to the operating Winding thereof, a source of timing impulsesfor operating jointly with either of said receiving relays the lgas-iilled electron discharge tube connected-to the transmitting relay associatedY withv theother line to cause' operation of that transmitting relay -t'o'spacing condition,` and a gas-lled electronv discharge tube individualto each of'sa-id firstementionedtubes and operable jointly by saidsource of timing impulses and either of said'receiving relays upon restoration thereof to' markingA condition responsive to a marking signal for 'quenching the operated one offs'a-i'd `'rst'mentioned tubes to restore its associated transmitting relay to `lmarkinig-v condition;

6)" In-'a' regenerative `tel'egrapli repeater, an in comingv line loop including signal receiving means, anoutgoing' line loop including'-transmitW ting-means euatpt'edl tointerrupt said outgoing linefloop', fa sour'ceoftiming-impulses, agas-lled electron discharge `tiubenhaving its anode connected to said transmitting mea.nsfandoperable jointly by'said Source`-oftiming impulses and seid receiving-meansuponresponse of the latterlto aspacing AsignalV for causing said transmitting means to intermpt'said outgoing line loop, and a gas filled` electron discharge tube independent of' saidtransmi'ttingmeans and operablejeintly by said source of' timing impulses: andl said rev ceivingfmeansfuponresponsevof the latterl to a marking signalior quenching said rs't-men--Y ti'ned-tube tocause-A said transmitting means to reclos'esaid outgoingflinek loop solely' as a result 'Y of said'- quenching'.

'7'.'Inf a telegraph repeater, a rst line-termi-r4 nating loopiincludinga receiving relayf andftheanode# cathode dischargepathfof/a laorfrnally conVv` ductive' 'gri'dLcont'rolled electron discharge tube;

a second--lineiV terminating' loop f Vincluding 'a re'- ceiviirg relay land tlief anode-cathode discharge' path of a normally conductive: gridc'ontro'lledfl electron discharge tube, meansV controlled Iby either' of- `saidi."receivingf` relays" uponJresponsel' thereof' toa spacing signalfforrapplying af cut-off potential-',tolthefgrid'of the electron discharge tube associated'vvith theother looptocau'se the? retransmission orf a spacing signal and'forlholding the receiving relayasseciatezl -With said other Y' loop1injmarling` condition, and means Lcontrolled by thevsame vreceiving relay upon responsethere-v` of toamarkingv signal for raising the-potential of 1 the grid of tue-tube 'associatedwitn saiefbther loopto restoresaidtube toconductivityvvv I 8.-'I`n aregenerative'teleg-raph repeater;v .incoming-flineloop including the openating-Winding ofareceiving4 relay, an outgoing Aline loopincluding the anode-cathode dischargey path of a; normally4 conductive grid-'controlled electrondis} charge tube,` asourceff-ti'rning impulses, aifgas=- lled electronidiscljlarge tubecontroll'ablej jointly.' by lsaid sourcey oftim'ing impulses and said relay upon response thereof: to a spacing signal for ap` plying a'cut-oi potential' to the grid of said' vrs-tmentioned tube to cause the transmission of "ai spacing'signal oversai'dloutgoing line loop,h and ags-lled electron discharge tube controllable' jointlyby said source of timing impulseseandi'sa'd' relay uponirespoiisthereofito aemarkngffsifgnal for' quencl'iing:v said#:secondamentioned-tube to] re-L storelsaidif'rstementioneftube to conductivity for transmittingzamarkinglsignallfover:saidhoutegoinglineloo'piv a regenerative.etelegraphvrepeater,a-.first linehterniinating l'oop including.` a receiving relay. an'dl the anode-cathode @discharges path;V off1= ai normally conductive:grim-controlled?electron dis charge-2 tuba-.-A a; 'secondi linext'efrminating :loopl i includings an;receivingM 1 relay` andi the anode-cathode discharge pathi. offs.V normally l conductivervgridcontrolled:V electroni. dischargetube, af source of: timing@ impulses; a4 gas-filled? electron discharge tube t individua to Landshavingi its= anode: corr-1 nected to the-:gridlioi each of said.'lineztenminat-y ing Sloopvr tubes: anni: controllable v4j ointly by: said; souri'zerfofv "timingtimpulses andfitheerece'ivingv re layA associated:l with: thef@ rother f line.y terminating loop."` uponi-re'sponse. of saidirelay: toi aspaicing-sia' nalfforapplyingaicuiropotentialtoasaid gri'dto causetheretransmission cria-:spacing signal; andi aigas'f'lledb-electrorr discharge; tube. indivi'dualf-to` each;l ci"- said;` rst-'lmentione'dgasallediftub'es and controllable lj'ointlyLbylrsaidsource otitimingslim pulsesiiand said?receiving:` relayiiupon restoration thereofA-'t marking. for quenchingfitheirfrespeee tivelyassociatefdonesmfl the firsii-mentionedYIg-as'- filled tubesito restore thecut-oilfone or sadli'nef. terminatin' loop tube'siftot conductivity-for: re transmitting amiarkingisignal;

IOln fa-regenerative telegraph repeater;V a.

'rst tele graph :line-having LaA receiving rrel'ayl and ai tr'ansmittingzre ay. associatedv'therew'ith, aseoond'ftele'grapliflne having"A ail-receiving relay and? a transmitting relajA associatedftherewith, a source-y off" timing' impulses, 'al 'gas-filled4 electron di`scharge tubehaving'fits anode connected to the transmitting relay associated-with oneV ofv saidl lines and op'erablejointly byfsaid--source off'tim ing impulses and the receiving-relay associated? Witlr -the`= other j"line i'for' operating the transmit- :first-'mentioned and saidfsecon-mentioned elecfn tron discharge tubes to restore thetransmitting relay associated' i sociatedwith the Same''li'neresponsive to Va spacf ing; signal. l

ljlfln 'afr'egenerativevftelegraph repeater; at first telegraphlinehavin'g afreceiving relay andi:

atransmit lnglrel'ay yassociatedtlierewith, a second telegraph'linehaving afreceiv'i'ngrelayv and a'- transmitting Arelay associated therewith', asource charge tnbeflialvingfits anode connected to thetransmitting'A relay associat'edwith one ofA said lines andoperable jointly by said"sourceofi-tim ing impulses-andthe receiving relay associated? tneff otl'iver' line Y for'f operatingY the Y transmit-- ting relayfassociatedWithsaid one lineA tospacing condition, a gas-filled electrondischarge tubehaving itsc anode connected toi awinding oiu'` the receiving relayasscciatedwith" said'f one line and Y K v /ithv-said one-'line tomarkingl conditionandtorender they receiving rela-y as-f 21 pefrable directly by the receiving relay asso-I ciated with said other line for holding the receiving relay associated with said one line in REFERENCES CITED Thel following references are of record in the le of this patent:

5 UNITED STATES PATENTS Number Name Date 2,101,243 Cummings Dec. 7, 1937 2,133,456 Kinkead Oct. 18, 1938 lo 2,237,631 Peterson April 8, 1941 

